Conventional articles of footwear include two primary elements, an upper and a sole assembly. The sole assembly is secured to a lower portion of the upper and is generally positioned between the foot and the ground. The upper and the sole structure operate cooperatively to provide a comfortable structure that is suited for a wide variety of activities.
The upper provides a covering for the foot that comfortably receives and securely positions the foot with respect to the sole assembly. The upper is often formed of leather, synthetic materials, or a combination thereof and comfortably secures the footwear to the foot, while providing ventilation and protection from the elements.
The sole assembly may provide cushioning, traction, and wear resistance. The sole assembly generally incorporates multiple layers that are conventionally referred to as an insole, a midsole, and an outsole.
The insole is a thin cushioning and compressible member, located within the upper and adjacent the foot's plantar surface so as to enhance footwear comfort.
The midsole, which is traditionally attached to the upper along the entire length of the upper, forms the middle layer of the sole assembly and serves a variety of purposes that include controlling potentially harmful foot motions, attenuating ground reaction forces, and absorbing energy.
The outsole forms the ground-contacting element of footwear and is usually fashioned from a durable, wear resistant material that includes texturing to improve traction.